WIP removing SAS phy control from the ZFS test suite

Convert zfsd_replace_002_pos to use libgnop instead of libsas

tests/sys/cddl/zfs/tests/zfsd/zfsd_replace_002_pos.ksh
tests/sys/cddl/zfs/tests/zfsd/zfsd_test.sh

• Simulate disk failures with gnop, not sas phy control
• Reduce disk count to 3
• Reduce timeouts, so the test fails faster

The test is still disabled, because we never implemented this
feature in zfsd.

Sponsored by: Spectra Logic Corp